In many marine propulsion applications, a snap ring is used to securely position and mount items, such as bushings, to a shaft or pipe. In practice, the otherwise smooth shaft or pipe typically includes a shallow groove to help retain the snap ring in the desired position. Snap rings are pre-formed circular pieces of metal having an inner diameter slightly smaller than the external diameter of the pipe or shaft to which they are applied. The snap rings typically contain a small break or open section in the ring. To apply the snap ring, the ring is flexed outward to increase its circumference so that it can be slipped over the end of the pipe or shaft and positioned accordingly. Once the snap ring is in place, the external force is removed from the snap ring, causing it to return to its original size and securely hold it in place on the shaft.
In the past, hand operated devices have been used to provide the force needed to expand the snap ring. Typically, a snap ring pliers is used by workers on an assembly line to expand and apply the snap rings. The snap ring pliers require the worker to exert a contracting force on the handles of the pliers, which in turn expands the snap ring. In a production assembly line, a worker might use a pliers in this manner as many as 500 times daily. This task is both labor intensive and tedious.
Therefore, it can be appreciated that an externally powered snap ring applicator would be desirable, especially for applying snap rings on marine propeller and drive shafts.